Brake operated transmission clutches with fully-resetting modulator-load-piston

Abstract

A multi-functioning hydraulic transmission control circuit including interacting valve mechanism parts which, in response to a shift being called for in a clutch-cylinder-controlled multi-speed transmission, inaugurate a fill pressure flow to the clutch cylinders concerned, prior to the subsequent fluid pressure rise effected therein; thereafter, upon completion of the fill, the parts modulate pressure rise of the hydraulic clutch fluid from and at approximately actual clutch fill pressure up to, and remaining at, the final pressure of engagement. These functions including full resetting of the parts at the beginning of each shift, and a lesser and a least gradual pressure rise afforded during respective second and third speed upshifts, are all accomplished by and among a pair of direction-selector and orificed-speed-selector valve spools connected to the transmission clutch cylinders to direct valve fluid output thereto selectively, and also 1st, dump valve, 2d, simulated clutch piston, 3d, load piston, 4th, modulator valve, and 5th, interacting spring parts collectively providing said directed valve fluid output, all in a valve bore common thereto, and arranged therein with the dump valve part confronted at one side by the simulated clutch piston part so as to define mutually therewith a differential pressure chamber in the bore, and confronted at the other side by a first side of the load piston part so as to define mutually with that first side a signal pressure chamber in the bore, and with an opposite side of the load piston part spacedly confronting the modulator valve part so that they mutually engage therebetween the interacting spring parts in the common bore.

What is claimed is: 
     
       1. For use in a clutch controlled vehicle having activatable brake apply means for the vehicle brakes, a rate of rise hydraulic system having a connection to individual lines of a piston-type, transmission-clutch group, wherein the fluid output of the system undergoes pressure loss to an actual clutch fill pressure in order to pass from said connection through said individual lines to reach a selected clutch piston, said hydraulic system comprising: a clutch pressure modulating valve and signal pressure control means both reciprocally mounted and in opposite ends of a bore formed by a valve housing, said clutch pressure modulating valve being arranged to afford flow of the system fluid output to said connection, out of pumped fluid supplied thereto from a pump source;   said signal pressure control means comprising a dump valve member reciprocable toward and away from the adjacent end of the bore, and a differential pressure chamber defined between and by the dump valve member and said bore end and receiving system-output-fluid from said connection;   said dump valve member cooperating with modulator loading means in said bore to define a signal pressure chamber, and said dump valve member providing a fluid output;   means of connection from the dump valve member utilizing said dump valve fluid output to supply rising signal fluid pressure to the fluid inside the signal pressure chamber; and   neutralizer means and a selector valve member disposed in series in said housing in that order at said connection;   said neutralizer means delivering system fluid output to the selector valve member and responsive to activation of said vehicle brake apply means to withhold system fluid output from the selector valve member;   said selector valve member having spool valve portions effective in progressive selector valve positions for cooperating with said individual lines to direct, to selected ones of the clutch pistons, the system fluid output delivered by said neutralizer means.   
     
     
       2. For use in a power-shift vehicle having activatable brake apply means for the vehicle brakes: a rate of rise hydraulic system having a connection (conducting pressures P 1 , P 2 , P A ) to individual lines of a plurality of fluid operated piston type, power-shift, friction engaging drive devices (F-R), wherein the fluid output of the system undergoes pressure loss to an actual fill pressure of each device in order to pass from said connection through said individual lines to reach a selected fluid operated piston, said hydraulic system comprising: a pressure modulating valve (58) and signal pressure control means both reciprocally mounted and in opposite ends of a bore formed by a valve housing, said pressure modulating valve being arranged to afford flow of the system fluid output to said connection, out of pumped fluid supplied thereto from a pump source;   said signal pressure control means comprising a dump valve member reciprocal toward and away from the adjacent end of the bore, and a differential pressure chamber defined between and by the dump valve member and said bore end and receiving system-output-fluid from said connection;   said dump valve member cooperating with modulator loading means in said bore to define a signal pressure chamber;   first (186) and second (122, 124) means of connection from the dump valve member and selector valve member, respectively, utilizing system fluid output therefrom to supply rising signal fluid pressure to the fluid inside the signal pressure chamber; and   neutralizer means (44) and a selector valve member (54) disposed in series in that order at said connection;   said neutralizer means delivering system fluid output to the selector valve member and responsive to activation of said vehicle brake apply means to withhold system fluid output from the selector valve member;   said selector valve member having spool valve portions effective in progressive selector valve positions for cooperating with said individual lines to direct, to selected ones of the fluid operated pistons, the system fluid output delivered by said neutralizer means.   
     
     
       3. For use in a power-shift vehicle having activatable brake apply means for the vehicle brakes: a rate of rise hydraulic system having a connection (conducting pressures P 1 , P 2 , P A ) to individual lines of a plurality of fluid operated piston type, power-shift, friction engaging drive devices (F-R), wherein the fluid output of the system undergoes pressure loss to an actual fill pressure of each device in order to pass from said connection through said individual lines to reach a selected fluid operated piston, said hydraulic system comprising: a pressure modulating valve (58) and signal pressure control means oppositely disposed and both reciprocally mounted in a bore formed by a valve housing, with the pressure modulating valve in a first end and the signal pressure control means in a second end of the bore;   a load piston in the bore intermediate its first and second ends, and arranged with the signal pressure control means to form a signal pressure chamber therebetween in the bore;   spring means arranged for loading interaction between the load piston and said valve;   said signal pressure control means including a differential pressure chamber, with a simulated clutch fill piston therein affording an enlargement of volume of the differential pressure chamber during actual clutch fill;   means forming paths leading respectively:   from the valve assembly fluid output through the differential pressure chamber, thence through first means (186) in the signal pressure control means to the signal pressure chamber for causing a control stroke of the load piston against the spring means; and   from the signal pressure chamber thence through second means (174) in the signal pressure control means to drain, during actual clutch fill and corresponding enlargement of the differential pressure chamber by the simulated clutch fill piston therein; and   neutralizer means (44) and a selector valve member (54) disposed in series in that order at said connection;   said neutralizer means delivering system fluid output to the selector valve member and responsive to activation of said vehicle brake apply means to withhold system fluid output from the selector valve member;   said selector valve member having spool valve portions effective in progressive selector valve positions for cooperating with said individual lines to direct, to selected ones of the fluid operated pistons, the system fluid output delivered by said neutralizer means.   
     
     
       4. For use in a power-shift vehicle having activatable brake apply means for the vehicle brakes: a rate of rise hydraulic system having a connection (conducting pressures P 1 , P 2 , P A ) to individual lines of a plurality of fluid operated piston type, power-shift, friction engaging drive devices (F-R), wherein the fluid output of the system undergoes pressure loss to an actual fill pressure of each device in order to pass from said connection through said individual lines to reach a selected fluid operated piston, said hydraulic system comprising: a pressure modulated valve (58) and signal pressure control means oppositely disposed and both reciprocally mounted in a bore formed by a valve housing, with the pressure modulating valve in a first end and the signal pressure control means in a second end of the bore, said valve being arranged to afford flow of the valve assembly fluid output, out of pumped fluid supplied thereto from a pump source;   a load piston in the bore intermediate its first and second ends, and arranged with the signal pressure control means to form a signal pressure chamber therebetween in the bore;   spring means, arranged for loading interaction between the load piston and said valve;   said signal pressure control means having a differential pressure chamber, and having first means to transfer timing fluid from the differential pressure chamber to the signal pressure chamber for causing a control stroke of the load piston against the spring means, and second means to vent signal pressure to reduced value to reset the load piston during actual clutch fill, said differential pressure chamber being included in said signal pressure control means and with a simulated clutch fill piston therein movable to a chamber-enlarging position affording an enlargement of volume of the differential pressure chamber during actual clutch fill;   admission means (212) connected between the valve assembly fluid output and differential pressure chamber whereby, during actual clutch fill and corresponding enlargement of the latter by the simulated clutch fill piston therein, to admit the valve assembly output fluid to the differential pressure chamber at reduced pressure equivalent to signal pressure, effectively equalizing pressure across the signal pressure control means and enabling the load piston to fully reset against the equivalent of actual clutch fill pressure; and   neutralizer means (44) and a selector valve member (54) disposed in series in that order at said connection;   said neutralizer means delivering system fluid output to the selector valve member and responsive to activation of said vehicle brake apply means to withhold system fluid output from the selector valve member;   said selector valve member having spool valve portions effective in progressive selector valve positions for cooperating with said individual lines to direct, to selected ones of the fluid operated pistons, the system fluid output delivered by said neutralizer means.